SAIGON, South. Vietnam, Dec. 12 — The United States Navy's nuclear‐powered aircraft carrier Enterprise and task force of several amphibious ships and destroyers left Vietnamese waters Friday heading toward the Indian. Ocean for a possible rescue of American citizens from the East Pakistani capital of Dacca.

Naval commanders aboard the aircraft carrier Constellation, which has been operating with the Enterprise in the Tonkin Gulf, said today that the 90,000‐ton Enterprise and her escorts had orders to sail to the Strait of Malacca off Singapore to await final instructions to proceed up the Bay of Bengal.

[Officials in Washington said that the Soviet Union appeared to be reinforcing its naval strength in the Indian Ocean. Page 16. In Calcutta, foreigners evacuated from Dacca said that the Bengali population was fleeing the East Pakistani capital as Indian troops closed in. Page 16].

The officers aboard the Constellation said that the mission of the United States task force would be to evacuate Americans and other foreigners from Dacca.

It was possible, the officers said, that the Enterprise's mission would be canceled if the evacuation of American dependents and officials from Dacca could be completed by more normal means.

They said that the task force had reached a point a few hundred miles northeast of Singapore in the South China Sea by noon today.

“They were to get further orders when they got to Singapore,” one official said. “What will be decided then depends on the situation in Dacca.”

Other officers said that the plan was for the carrier's helicopters and planes to fly American and other foreign transports from Bangkok failed.

The Enterprise, the largest aircraft carrier in the United States fleet and the only nuclear‐powered one now in operation, carries about a hundred fighter‐bombers, bombers, fighters, reconnaissance aircraft, helicopters and small cargo planes. Her ordnance stores include nuclear bombs.

Three British C‐130's flew from Dacca to Calcutta today with about 480 British, American and German evacuees, according to United States consulate officials in Dacca. The Americans were said to number 125.

There was no official confirmation from the Navy or from the United States command in Saigon that the Enterprise task force had left the Tonkin Gulf or any official indication of what its mission was to be If it continued into the Bay of Bengal.

The departure of the Enterprise cut in half the number of missions being flown by the Seventh Fleet task force in the Tonkin Gulf against the Ho Chi Minh supply trail in Laos.

The Constellation, which remained on station, did not appreciably increase the number of her missions, but her stay in the Tonkin Gulf has been extended. Another carrier, the Coral Sea, is reported on the way.

The senior commander of the Seventh Fleet task force, Vice Adm. Damon W. Cooper, went with the Enterprise.

“I think it's the wisest thing to have done, because it could be delicate,” another high‐ranking officer said today.